Blizzard Entertainment revealed StarCraft II: Legacy of the Void at BlizzCon 2014. The game was playable at the showfloor.
Among the new units in this expansion are the Herc and Cyclone (Terran); the Lurker and Ravager (Zerg) and the Disruptor (Protoss).
However, old units for each race will be impacted with this new expansion with a few nerfs, and new upgrades or features.
Blizzard provided 3 gameplay videos showing off some of these radical changes.